With Haas to miss the first four games of the NRL season, an injury to explosive lock Pangai Jr was the last thing new coach Anthony Seibold needed ahead of his first season at the helm of the Broncos.

Pangai Jr will undergo scans on Sunday, but the Tongan powerhouse admitted he faced a fight to be ready for the opening to the NRL season.

"I felt it pop," Pangai Jr said.

"I'm pretty disappointed. I worked hard on my hamstrings all pre-season.

"I don't know what to say. I'll be all right, it's early days and we've got a long season ahead.

"Hopefully I'm good for round one. Hopefully I can get back on the horse, get my preparation right and be right for round one against the Storm.

"We've got a lot of depth and the young boys played well. If I'm out for round one I'm pretty sure we can cover it."

Tevita Pangai Jr suffered a leg injury and was forced off the field after 18 minutes. Picture: AAP

Flegler ran all over the Seagulls to bolt into favouritism to secure an NRL debut in the Broncos' season opener against Melbourne on March 14.

The 19-year-old has been likened to Broncos legend Shane Webcke and his steaming carries against the Seagulls proved the comparisons are warranted.

With Haas suspended this week following an NRL integrity unit investigation, Seibold is on the lookout for a new bench prop.